In electrical and electronic equipment, the electrical performance requirements for executing high-speed signal transmission correctly are that the frequency attenuation characteristics of a transmission channel existing between a driver and a receiver, both being an LSI (Large Scale Integration), are flat over a wide range.
To satisfy such electrical performance requirements, conventionally, the transmission channel in the electrical and electronic equipment is formed, for example, by using a high-class substrate material having a low dielectric constant, by using a connector for high-frequency transmission, and by accurate board design.
In recent years, designing for reproducing a signal waveform in a receiver finally appearing as a rectangular wave, by using an equalizer function of performing wave shaping and an automatic gain amplification function, of an LSI is becoming popular.
Particularly, when amplifying a high-frequency-range signal having a large SN ratio (signal/noise ratio) and a large attenuation amount, an equalizer that implements the equalizer function is required to have a capability of performing linear correction, so that the frequency amplitude characteristics of the amplified high-frequency signal are flat over a wide range. Hence, the LSI analog equalizer needs to have frequency characteristics that cover the high-frequency range as well. As a result, undesirably, for example, the crosstalk noise may increase and the circuit scale may increase.
A technique is also disclosed (for example, see Patent Literature 1) which flattens the frequency amplitude characteristics by disposing a directional coupler called filter in a transmission channel between a driver and a receiver.